The present invention provides a reflector for a flood light or luminaire which can be utilised for flood lighting purposes.
When in use, area luminaire products also known as flood lights, can exhibit one or more of the following disadvantages.
Hot spots (xe2x80x9chot spotxe2x80x9d is a term used to designate areas of light concentration) can occur on the ground being lighted by floodlights. The unevenness produced in the area lit by one flood light is produced by variable amount of light falling on the surface area to be lighted. In lighting installations for security and other purposes, this problem can be overcome by provision of many lights lighting a particular area, all being directed so that adjacent and opposite flood lights will xe2x80x9cfill in the gapsxe2x80x9d or even out the amount of light over the total area. Such additional lights can result in high additional costs because of the need for more light fittings, additional cable laying and control systems; and higher operating costs for the owners.
Another disadvantage which may be exhibited by lighting systems in the market place is that the cut off, (xe2x80x9ccut offxe2x80x9d is a term referring to the clear division between lighted and non-lighted areas which prevents light falling on areas on which light is not required), is not sufficient to meet increasing standards for cut off from lighted installations as described in Australian standard 4282.
Another disadvantage of flood light construction of the prior art is that they are designed for use with a particular lamp, but when the lamps are improved and new and better lamps enter the market, the reflectors are not able to work as originally designed with the new lamps. Once the older globes are no longer in the market place, the reflectors and light fittings may need to be replaced because they no longer work as designed with new technology lamps.
Prior art luminaires in achieving the cut off demands for lighted installations detailed in AS4282 have, to date, not been able to produce a distribution of light that would look substantially even to the naked eye, over the lighted area, from a single lamp, without the assistance of additional lighting products.
This standard in Australia, and a similar standard in Europe and other countries, will become more important as environmental limitations, such as the prevention of unwanted light from spot lights falling into residential areas, farming or other areas, become more enforceable in Australia and other jurisdictions.
It is an object of the present invention to provide a reflector and or a flood light which ameliorates, at least in part, at least one of the disadvantages of the prior art.
The present invention provides a reflector having at least three segments, each segment having a part parabolic shape in cross section or side elevation, all segments having the same cross section across a major portion of their width with a common focal line, said segments having a common focal point located on said focal line at approximately the mid-point of said focal line, said parabolic segments being able to reflect a parallel beam of light that originates from a source located at said focal point or along said focal line.
The present invention provides a reflector having a parabolic portion or more than one part parabolic portions which includes at least a first portion having a specular reflecting sheet and a second portion having a concentrating or concave peened reflecting sheet, said first portion occupying an area of said reflector which area is located intermediate of the width of said reflector and said second portion occupying an area adjacent to said first portion said second portion also being located intermediate of the width of said reflector, said parabolic or part parabolic portions having a focal point at which point the centre of a lamp is positionable, said focal point being at a minimum focal distance from said parabolic portion or one of said part parabolic portions, said minimum distance defining a focal length of the parabolic portion or one of said part parabolic portions, said reflector terminating at a rim which is contained in a single plane.
The present invention also provides a flood light including a main reflector surface and two side reflectors, said main reflector surface having at least two part parabolic portions, a first part parabolic portion being made from a specular reflecting sheet and a second part from concentrating or concave peened reflecting sheet each of said reflecting sheet positioned centrally of said reflector surface, said first part parabolic portion occupying the area of from a rim of said main reflector to a first intermediate location of said main reflector surface and said second part parabolic portion occupying an area from said first intermediate location to a second intermediate location, each part parabolic portion being characterised by having a common focal point at which the centre of a small arc metal halide lamp or other small arc lamp is positionable, wherein the smallest focal length part parabolic portion is that portion which is includes all of the specular reflective sheeting, with said first and second part parabolic portions including said concentrating or concave peened reflective sheeting, said main reflector surface having the following dimensional features:
a) the parabolic distance occupied by said specular reflecting sheet on said parabolic portion or part parabolic portion is some 3.8 times said smallest focal length;
b) the parabolic distance occupied by said concentrating or concave peened reflecting sheet is some 3.4 times said smallest focal length;
c) the width of the specular reflecting sheeting and the width of said concentrating or concave peened reflective sheeting is the same and is approximately 3 times the smallest focal length;
d) the perpendicular height of said reflector above a plane which includes a rim of said reflector, is approximately 4.8 times said smallest focal length;
e) the width of the opening of said reflector at its rim is some 9.6 times said smallest focal length;
f) the perpendicular distance between a line perpendicular to the plane of said rim which perpendicular line is tangent to said reflector at the reflector""s left hand extremity and a second line which is parallel to said perpendicular line through the right hand extremity of said reflector, is some thirteen to fourteen times said smallest focal length of said parabolic portion;
g) the length of the opening of the reflector from its forward rim to its rearward rim is 12.9 times said smallest focal length; and
wherein said first part parabolic portion is contoured and oriented to provide a main beam emitted in a direction of 55 to 65 degrees to a direction normal to the plane of said rim and said second part parabolic portion is contoured and oriented to provide a main beam emitted in a direction 45 to 55 degrees to a direction normal to the plane of said rim, said flood light including a visor which when light from said lamp hits it at some 50 to 65 degrees to a direction normal to the plane of said rim, said visor will reflect light, and wherein the rest of said main reflector surface and said side reflector is comprised of spreading or convex peened reflecting sheet.
The present invention further provides a reflector surface having a first, second and third part parabolic portions having a common focal line, said first part parabolic portion having the smallest focal length and beginning at one rim, the third part parabolic portion having the longest focal length and terminating at a rim opposite said first mentioned rim, said first and third part parabolic portions being connected by said second part parabolic portion having a focal length intermediate the focal length of said first and third part parabolic portions, the change over from said first part parabolic portion to said second part parabolic portion occurring at an angle of some 0 to 10 degrees to the vertical measured at the common focal point or line, and the changeover from said second part parabolic portion to said third part parabolic portion occurring at some 50 to 80 degrees to the vertical measured at the common focal point or line; said first part parabolic portion reflecting a main beam at an angle of between some 55 to 65 degrees from the vertical, said second part parabolic portion reflecting a main beam at an angle of some 45 to 55 degrees from the vertical, and said third part parabolic portion reflecting a main beam at an angle of some 25 to 45 degrees from the vertical, each of said change over between adjacent part parabolic portions being such that tangents to adjacent part parabolic portions at their theoretical point of intersection have an angle between the tangents of between 0xc2x0 and 5xc2x0.
The present invention also provides a floodlight having a reflection surface formed from three parabolic segments and two reflective sides, said flood light including a visor to reflect light from said visor onto said reflection surface, said flood light being characterised by having 3 main beams reflected from a light source off each of the parabolic segments and fill light directly from said light source, and wherein additional fill light is provided by means of light reflected from said visor subsequently being reflected from said parabolic segments and out through said visor, said flood light producing defined cut offs in at least the forward and rearward directions.
A flood light or luminaire containing a reflector which is an embodiment of the above inventions can produce an improved distribution of light in the area lit by the flood light, and yet maintain a level of cut off which allows the lighted installation to meet the demands of AS4282 or similar standards.
An illuminance, which to the naked eye will appear more uniform than that produced by the prior art, occurs from directly below the flood light out to 60 degrees from the vertical and within or along an arc of 60 degrees from directly below the flood light in the horizontal plane.
These features may result in less light fittings and lamps being utilised to light up a desired area by comparison with prior art constructions, together with a corresponding reduction in the amount of cabling, controls and labour and operating costs for installation of all this equipment.
The above definitions of the inventions are directed to features, which at the time of writing are thought to be essential to those inventions. At a later date, it may be necessary to combine with those essential features, features which are at this time inessential features or are indicated as being preferable, so that currently inessential or preferable features in combination with essential features identified above, will result in an invention or invention differentiated from prior art, which may come to light at a later time.